Thermostatic relay



Aug. 24, 1954 o. A. JOHANSEN THERMOSTATIC RELAY 3 Sheets-Sheet 1 Filed May 16, 1952 g- 1954 o. A. JOHANSEN THERMOSTATIC RELAY Filed May 16, 1952 3 Sheets-Sheet 2 Aug. 24, 1954 o. A. JOHANSEN 2,687,460 THERMOSTATI C RELAY Filed May 16, 1952 3 Sheets-Sheet 3 I77 VQWZLOF OZav- A. tfiakansen Patented Aug. 24, 1954 UNITED STATES PATENT OFFICE 2,687,460 THERMOSTATIC RELAY Olav Amandus Johansen,

Elek

signer to El-Ka Langhus, Norway Langhus, Norway, astrisk Apparatfabrikk,

Application May 16, 1952, Serial No. 288,350 Claims priority, application Norway May 23, 1951 5 Claims.

This invention principally relates to an electric thermostatic relay. One of the objects of the invention is to provide special means in connection with a relay of said type, whereby the for different purposes.

According to the invention this part of the problem is solved by providing the relay with an electric heating element and a bimetallic rod or According to the invention these two elements, the heating element and the bimetallic rod are so related to each other that the heat action of the heating element upon the rod may be varied.

In a preferred embodiment of the invention,

rangement, so that the bimetallic rod may contact the actuating organ at different places, that is against the diilierent steps, according to the axial adjustment of the bimetallic rod in relation to the heating element.

In a preferred embodiment of the invention said step-arrangement takes the form of a slot or cut-out in said arm of the actuating organ, so that the bimetallic rod may act upon the arm in both directions, a backlash for the bimetallic rod occurring from the same acting upon the arm in one direction thereof until it acts upon said arm in the other direction.

Further the invention relates to a special arrangement of the electrical contact organs of an electric thermostatic relay of the above mentioned type. In this connection the object of the invention is to provide contact organs which will have a snap action in the opening as well as in the closing of the contacts, so that rapid connection and rapid disconnection are obtained, and no sparks will occur.

attached to the frame of the relay in such manner that the two springs extend in directions towards each other. By suitable choice of the lengths of these two springs is obtained that the rollers are at any time resiliently contacting each other, but

According to the invention the arrangement may be of special value in connection with electric relays intended for breaking of a current flow after a predetermined period of time.

for heat treatment of a work for a certain period, c. g. a slice of bread to be toasted.

Electric toasting apparatus are well known in which a slice of bread is placed between two heating elements and release devices are provention is made use of by providing the toasting apparatus with a spring actuated frame which normally keeps the slice of bread in raised posiof a holding magnet. According to the invention the frame when being moved downwards establishes contact between said spring supported secondary contact which is maintained open by the actuating organ as long as the bimetallic rod is cold, but which is closed when the bimetallic rod curves due to heating thereof. Just before opening of the contact providing current supply to the heating element of the thermostat said contacts are closed, whereby a circuit to the electromagnet is established through a suitable resistance, so that the slice of bread, or the like is continually heat treated. Only when the bimetallic rod of the thermostat straightens and presses in opposite direction against the actuating member the contact providing current to the electromagnet is opened, and the frame carrying the slice of bread is raised to move said slice away from the heating element used for toasting the bread. The device now is ready for performing the same operation once more.

In order that the invention may be easily understood it will below be described in connection with the drawings which disclose an embodiment of the thermostatic relay according to the invention with diagrammatical indications of arrangements for the electric apparatus thermostatically controlled by means of this thermostat. In the following description also other technical features covered by the invention will be described.

Fig. 1 is a perspective view of a thermostatic device according to the invention with a wiring diagram for an electric apparatus controlled by the thermostat.

Figures 29 illustrate, diagrammatically. different positions of parts of the thermostat, to explain the operation of the thermostat. Thus Fig. 2 showns the thermostat when carrying no current. 1 1 E T Fig, 3, right part, shows the thermostat at the moment when current is supplied to the heating element. i

Fig. 4 illustrates the bimetallic rod in its first phase of downward bending.

Fig. 5, right part, illustrates the bimetallic rod in its last phase of downward bending.

Fig. '7 corresponds to Fig. 4, but shows the bi metallic rod displaced further forwards in relation to the heating element.

Fig. 9 is a corresponding view but with the bimetallic rod moved fully backwards. Fig. 2, right part, shows the contact device of the thermostat in free position. Fig. 3 shows the contact device after the thermostat having been started. Fig. 4 shows the contact device after the bimetallic rod having started to act upon the actuating member, and Fig. 5 shows the contact device when the actuating member interrupts the circuit to the heating element of the thermostat. Fig. 6 shows the bimetallic rod and the actuating memher, after the last phase of a period of time, the position being the same as in Fig. 2.

On Fig. 1 of the drawings numeral l designates. the frame of the thermostat. 2 is the electric holding magnet for the work to be treated. 3 is the main heating element used for treatment of the work. 4 designates a resistance.

On the thermostat frame I is provided a heating element 5 having electrical voltage supplied thereto through wire it, holding magnet 2, wire ll, terminal [3, bar l9 and wire 20, and back through wire 2 I, contact springs 22 and 25, double-contact spring 26, bar 2i, terminal 28 and wire 2930. Below the heating element 5 is provided a bimetallic rod 6 attached to an arm 7 which by means of a control member 8 may axially displace the bimetallic rod 6 in relation to the stationary mounted heating element 5. The bimetallic rod 6 has a nose 39 adapted to be received within a stepped or inclined opening [2 in one arm 9 of a two-arm actuating member 9-H!, which is pivoted on the frame at H, the free end N3 of its other arm serving to act upon the contacts for controlling the current passage when the relay is operating.

The function and operation of the relay is best understood by reference to Figs. 2-9. The right parts of Figs. 2-6 exactly illustrate the operation of the bimetallic rod. in connection with the actuating organ.

Fig. 2 illustrates the device in inoperative position thereof, that is prior to voltage having been impressed upon the heating element 5, this Figure showing the bimetallic rod ii its position of rest. Fig. 3 shows the device at the moment when the element 38 has been pressed down and voltage has been supplied to the heating element 5. Fig. 4 shows the device when the bimetallic rod has started to bend downwards and has abutted against the middle step it of the arm t. Fig. 5 shows the situation when the bimetallic rod 5 has become entirely bent and the actuating arm ace has been swung as far as possible for releasing element 5. 7 shows the same situation as Fig. 4 but in Fig. 7 the arm 7 has been moved forwards by means of the control member 8, so that the bimetallic rod 5 abuts against the lowermost step It of the actuating arm 9. Fig. 8 shows the same situation as Fig. 4 but in Fig. 8 the arm i has been moved forwards by means of the control member 8, so that the bimetallic rod 6 abuts against the middle step M of the actuating arm 9. Fig. 9 shows a situation similar to Figs. 4 and 7, where the bimetallic rod 6- has been moved backwards so that it abuts against the top step it of the actuating arm 9.

As will be understood the described simple arrangement makes it possible to obtain, by axial displacement of the bimetallic rod, different lengths of periods of time in the swinging movement of the actuating arm El-li3, whereby the period elapsing from start to end of the operation of the device may be shortened or lengthened.

The left parts of Figs. 2-5 show the same left end as that of Fig. l and illustrate a special contact arrangement suitable for use for example in connection with a bread slice toasting apparatus. Of special importance is here that the contact arrangement is such that a snap action is obtained and formation of sparks between the contact is prevented. A leaf spring 25 carries a contact 3! cooperating with a contact 32 for providing flow of current from terminal 28 through the bar 21 and the double-contact spring 25 to the heating element 5 of the thermostat. At its outer end the spring 25 carries a roller engaging a roller 23 carried by a leaf spring 22 which is attached to a supporting spring 3? which is secured to the frame of the relay and which extends in a direction opposite to that of the leaf spring 25. The lengths of the leaf springs 25 and. 22 are so chosen that the rollers contact each other. Closing of contacts 3l-32 take place by pressing the 2,687,460 6 Organ 3 d wnwa ds against the Sp 25 Wherewill snap past each other with snap action to by the Contact members 3| and 32 make contact cause fixed contact engagement between the said and the rollers 23 and 24 at the same t move contacts or will, with snap action, move said conm t p i ion Shown on Fig. 2 to that shown tacts away from each other, and said actuating 011 Fig. e e y a C cuit is Clo ed t ou h the 5 arm upon heating of the bimetallic member proheating element 5, wire 2|, sprin 2 rollers 23, vides said pressure against the first-mentioned 24, p i 2 c ntacts 3l32, sp in 26, b 21, leaf spring to open the contacts. terminal 28, wires 293ll and back to the source 2' A thermostatic relay according to claim 1,

of voltage.

Another spring 36, which is coupled in parallel to so t t t t to the bar I9 through the holding magnet 2 and t t afltuatv'ng the resistance 4, carries a contact 33 which 00- tants that is pened when t bimetallic member operates with a contact 34 connected to the dew is hot and t nd set of contacts is opened ble-contact spring 26, the bar 21 and the terminal when the bimetallic member-1s 1 28. Said contacts are open during the first part 3, A t t t r of the operation period but are closed just before in which a Second Se tuating organ 9-40, as Will be understood from tacts that and inspection of Fig. 4. Thereafter the ac- 2o hem-S hot and the eeeo g tuating organ 9 l0 continues to rock whereby When the bimetallic the spring with roller 24 snaps past the roller a, heating e1emeht i 23 and contacts 3l-32 are opened, so that the the hhmetalhe me supply of current to the heating element 5 is beincr Closed than interrupted. 25

Just before the opening of contacts 3l32 a becomes hot and t circuit, previously described, is closed over contacts 3334, the double-contact spring 26, bar 27, terminal 28 and wires 29 and 36, back to the source of current, see Fig. 5. As the bimetallic 30 Second Set f contacts are opened rod now is cooled it swings back and presses the A thermostatic relay according to claim 1, actuating Organ in the opposite direction in which said actuating member consists of a two-armed lever pivotally mounted on the frame each other, and the situation becomes that shown of the thermostat, one of the lever arms being 0I1Fig11eS2and The holdmg magnet 2 now Is inclined to form abutments for the bimetallic member at the difierent positions of the latter.

frame of the member and is provided mounted adjacent the bimetallic relay, and in which the bimetallic member is displaceable longitudinally thereof to vary its free length.

I claim:

1. A thermostatic relay having an actuating member comprising a frame, a bimetallic memwhich is controlled by the bimetallic member, a R f r it d in t file of t patent UNITED STATES PATENTS siliently abutting against the roller carried by the N m Name Date first-mentioned leaf spring and secured to the 1, 10,915 Alden Dec. 14, 1926 frame, the leaf springs being directed towards 70, 4 Eaton Aug. 22, 1939 each other, a contact mounted on the first-men- 2,172,189 Clark Sept. 5, 1939 tioned leaf spring and a contact mounted on the 2,358,372 Wolfner p 4 frame adapted to contact the contact on the 2,384,372 Eaton Sept. 4, 1945 first-mentioned leaf spring, the two rollers when 2,414,531 Johns Jan. 21, 1947 pressing against the first-mentioned leaf spring 21554321 Brosseall 14, 1951 

